Hydrolysis and transpeptidation of lysine peptides by trypsin

Abstract

The synthesis of L-lysine amide, L-lysylglycine amide, glycyl-L-lysine amide, di-L-lysine amide, [alpha]-benzoyldi-L-lysine and [alpha]-benzoyltri-L-lysine is described. a-Benzoyltri-L-lysine is rapidly hydrolysed by trypsin to [alpha]-benzoyllysine and dilysine. [alpha]-Benzoyldi- L -lysine is almost resistant to trypsin. Chromatographic analysis showed that although glycyl-L-lysine amide is hydrolysed rapidly by trypsin to glycyllysine and ammonia, L-lysyl-glycine amide is attacked by trypsin slowly, yielding dilysine in addition to glycyllysine amide and lysine. The chromatographic analysis of the incubation mixtures with trypsin of L-lysine amide, di-L-lysine amide and tri-L-lysine proved that transpeptidation as well as hydrolysis take place. A quantitative chromatographic analysis of the reaction products formed on incubation of tri-L-lysine with trypsin showed that the tripeptide is transformed almost quantitatively into dilysine. Tetra-, penta-, and hexa-lysine appear in the incubation mixture. The inhibitory effect of [alpha]-amino and [alpha]-carboxyl groups on the trypsin-catalysed hydrolysis of an adjacent lysyl peptide bond is discussed.